When it rains or in cold weather, a driver always shuts all vehicle windows to protect himself/herself from catching a cold or getting wet. However, this will cause a higher in-vehicle temperature different from the outside temperature and therefore cause the windshield to be covered with moisture. As a result, the vision of the driver will become obscured so as to adversely affect driving security.
Generally, there are two ways to eliminate the moisture. One is to activate the air-conditioner, and the other is to wipe the windshield manually. The former takes effect slowly, while the latter requires manual actions and is quite dangerous when the vehicle is running, especially on a highway. Moreover, some vehicles, such as delivery cars or camions, are not provided with air-conditioning devices and some vehicles may be equipped with poor or damaged air-conditioning devices. In this case, the moisture attached to the windshield must be eliminated manually, thus causing great inconvenience.